1. Mod 1 Copyright: JR Hendershot 2012
ELECTRIC MOTOR DESIGN Tutorial Lectures Instructor: James R Hendershot September 2012
Mod 1 Copyright: JR Hendershot 2012

2. Introduction to motor design lectures
(37) lectures are presented covering practical design procedures for three types of electric machines which each use the same or similar stators including cores and phase windings.
The first (15) lectures cover the topics that are common to all three machine types pertaining mostly to sizing, material selections & stators
For IMs (induction rotors) there are (7) lectures
For RSMs (reluctance synchronous rotors) there are (4) lectures
For PMSM, SPM & IPM types of PM rotors there are (6) lectures
An additional (5) lectures are added for general topics for thermal, mechanical, manufacturing and future challenges for machine design.
These lectures are intended for engineers who have a basic understanding of the theory of electric machines. This material is intended to supplement that eclectic machine theoretical background
Mod 1 Copyright: JR Hendershot 2012

3. Electric Machine Design Course
History & Introduction of Electric Machine Types
Lecture # 1
Mod 1, Copyright: JR Hendershot 2012

4. First known Electric Motor
Microscopic Bacteria Propulsion Motors
Plastic model of motor
Mod 1, Copyright: JR Hendershot 2012

5. Mod 1, Copyright: JR Hendershot 2012
Spark Museum
1312 Bay Street
Bellingham WA 98222
Tel:
Early examples of electric machines and other devices
Early TESLA
AC Motor
Mod 1, Copyright: JR Hendershot 2012

6. From Faraday’s law of Induction (1831)
Tesla & others developed the uses
of interactions of electric currents & magnetic fields produce mechanical forces that when properly configured
produce rotation torque and power.
Mod 1, Copyright: JR Hendershot 2012

7. Electric Motor Development (last 150 years)
First motors in mid 1800’s were DC powered by poor batteries
Edison employees developed practical DC machines for DC grid power
Tesla patented the AC motor and the AC grid system in late 1800’s
Electric motors are revolutionizing industry and products to this day
Classical classroom motor for Modern classroom Dyno-Kit
instruction called St Louis Motor for classroom instruction
Mod 1, Copyright: JR Hendershot 2012

8. Basic motor types for first 75 years
DC motors (wound rotor & commutated) Battery powered DC supply or M-G set powered AC motors powered with Hz grid AC Induction & AC synchronous AC or DC powered Series wound commutated
Mod 1, Copyright: JR Hendershot 2012

9. Motor types from most recent 50 years
Electronically controlled for variable speed or servo Stepping motors, VR, PM & Hybrid PM Brushless & PM-AC synchronous PMSM AC Induction V/Hz & flux vector controlled ACM Switched Reluctance SRM Reluctance Synchronous RSM Radial, Axial or Transverse flux versions
Mod 1, Copyright: JR Hendershot 2012

10. Mod 1 Copyright: JR Hendershot 2012
TESLA Family Tree
SMMA
Mod 1 Copyright: JR Hendershot 2012

11. Electric Machine Definitions
An electric motor is a rotating machine that converts electrical energy from some external power source (can be DC or AC) into mechanical energy across the air-gap between the stationary motor part and the rotating motor part.
An electric generator is a rotating machine that converts mechanical energy into electrical energy. The rotating part is driven by some external prime mover & electric power is produced across the air-gap.
Both can be same machine with opposite energy flow
Mod 1, Copyright: JR Hendershot 2012

12. Magnetic Field Sources
1- Earth’s magnetic field
2- Inner planetary magnetic fields
3- Nuclear magnetic fields
4- Permanent magnet fields
5- Electro-magnetic fields
6- Super Conducting magnetic fields
Mod 1, Copyright: JR Hendershot 2012

13. Magnetic Field created by permanent magnets
Permanent bar magnet in open circuit.
Flux lines extend from north pole to south pole through air or space.
Mod 1, Copyright: JR Hendershot 2012

14. Magnetic Field created by electro-magnets
flux S
Magnetic field from current flowing through the coil wrapped around magnetic iron focuses magnetic flux across an air gap.
Magnetic field produced by a coil with current flowing.
Mod 1, Copyright: JR Hendershot 2012

15. Machine flux linkage overview
Two categories of electric machines: (many types in each)
Non Salient pole & salient pole machines
Salient poles exhibit mainly attractive tangential gap forces
Non-salient poles exhibit both attractive & repulsive gap forces
Torque/amp produced by magnetic flux linkage for motoring
Voltage/rev produced by magnetic flux linkage for generating
Mod 1, Copyright: JR Hendershot 2012

16. Motors with permanent magnet rotors
Original motors of this type called PM Brushless (BLDC).
Evolved as outside-in (PMDC) commutated motors.
Electronically commutated by switching DC voltages
to each phase.
Open circuit back EMF shape between square & sine.
Only SPM types powered with DC phase switching.
(BLDC) motors re-named to (PMSM) when driven by sine hysteresis or Id & Iq current similar to an (IM) machine.
Both motors are same with different drives
Back emf can be identical to original
IPM versions must be Id & Iq controlled.
Mod 1 Copyright: JR Hendershot 2012

17. DC-AC Drive control chart for motor types
Mod 1, Copyright: JR Hendershot 2012

18. Motors designs included in this lecture series
(IM) AC induction machines, inverter driven
(RSM) Reluctance Synchronous machines
inverter driven
(PMSM) Permanent magnet synchronous
machines
Mod 1 Copyright: JR Hendershot 2012

19. Similar characteristics of (IM), (RSM) & (PMSM) motor types
Same stator core designs & windings
Same stator manufacturing infrastructure
Same use of active magnetic materials in stator
Similar power inverter topologies using Id & Iq control
Note: Each of the three machines types requires a special rotor design an configuration
Mod 1 Copyright: JR Hendershot 2012

20. Three rotor configurations using similar stators
RSM
PMSM IM
Motor template cross sections by Infolytica
Mod 1, Copyright: JR Hendershot 2012